ABSTRACT
Objective To explore the feasibility of dual-source CT coronary angiography (CTCA) using 80 kV tube voltage setting in patients with low body mass index (BMI).Methods A total of 240 patients with suspected coronary artery disease (BMI range 18.6-21.5 kg/m2) underwent dual-source CTCA.They were randomly assigned to group A (120 kV tube voltage),B (100 kV tube voltage) and C (80 kV tube voltage) based on a random number table.The contrast media dose,volume CT dose index (CTDIvol),dose length product (DLP),and effective dose (ED) were evaluated for each patient.Image noise,CT value,contrast,signal-to-noise ratio (SNR),contrast-to-noise ratio (CNR) and figure of merit (FOM) of coronary artery were all evaluated.Tie image quality of coronary artery was assessed with a threepoint scale (3 points:excellent,2 points:general,1 point:poor).Scan length,CTDIvol,DLP,ED,and contrast media dose for patients,image noise,CT value,contrast,SNR,CNR,and FOM of coronary artery were all analyzed using one-way ANOV4 analysis for 3 groups.Time windows of ECG-pulsing protocol were analyzed using x2 test,and the image quality scores of coronary artery were analyzed using Kruskal-Wallis test.Results There were no differences in scan length and Time windows of ECG-pulsing protocol among 3 groups (scan length F =2.58,P ＞ 0.05,Time windows of ECG-pulsing protocol x2 =0.77,P ＞ 0.05).The average contrast media doses were (82.0 ± 6.4),(76.8 ± 6.1),and (59.1 ± 3.5) ml,the average CTDIvol were(27.5 ±6.2),(18.7 ±4.4),and(11.4 ±2.4)mGy,the average DLPs were (427.7 ±92.4),(295.4 ± 77.1),and (183.9 ± 41.3) mGy · cm,and the average EDs were (6.1 ± 1.3),(4.1 ± 1.1),and (2.6 ± 0.6) msy for group A,B and C,respectively.There were statistical differences in contrast media dose,CTDIvoI,DLP,and ED among 3 groups (the F values for contrast media dose,CTDIvol,DLP,and ED were 383.08,248.13,221.05,and 234.81,respectively,all P ＜0.01).Compared to group A and B,the contrast media dose in group C decreased 27.9％ and 23.0％,and the ED decreased 57.4％ and 36.6％,respectively.The average image noise was (22.6 ±2.2),(26.1 ±3.0),and(29.1 ±3.4)HU for group A,B and C,respectively,and there was statistical difference in image noise among 3 groups (F=101.32,P ＜0.01).The average CT value,contrast,SNR,CNR and FOM were (438.3 ± 66.3)HU,(517.3 ± 67.8)HU,19.5 ±2.8,23.0 ±3.0,and 92.9 ± 31.0 in proximal RCA and (440.2 ±59.9) HU,(509.5 ± 62.6) HU,19.6 ±2.6,22.7 ±2.9,and 90.1 ±29.7 in LMA for group A,(534.2 ± 68.8) HU,(628.9 ±70.0) HU,20.7 ± 3.2,24.3 ± 3.6,and 157.6 ± 59.8 in proximal RCA and (528.4 ± 61.2) HU,(607.9 ± 71.2) HU,20.4±3.0,23.5 ±3.4,and 147.6 ±57.6 in LMA for group B,and (602.1 ±78.8)HU,(696.8 ±83.3) HU,20.8 ± 2.9,24.1 ± 3.2,and 239.3 ± 74.8 in proximal RCA and (592.5 ± 72.3) HU,(671.8 ±82.5) HU,20.5 ± 2.5,23.2 ± 3.0,and 221.8 ± 65.7 in LMA for group C,respectively.The CT value,contrast,SNR,CNR and FOM of coronary artery for group C did not decrease (the F values for CT value,contrast,SNR,CNR and FOM were 106.06,119.90,4.69,3.70,and 127.50 in proximal RCA,and 111.79,101.57,2.68,1.39,and 123.00 in LMA,and the P values were ＜0.01,＜0.01,＜0.05,＜0.05,and ＜0.01,in proximal RCA,and ＜0.01,＜0.01,＞0.05,＞0.05,and ＜0.01,in LMA,respectively).Image quality was rated as excellent,general and bad for 631,330,and 37 segments in group A,640,323,and 41 segments in group B,and 615,348,and 45 segments in group C,respectively,there was no significant difference in image quality scores among 3 groups (x2 =1.90,P ＞ 0.05).Conclusion For the patient with BMI≤21.5 kg/m2,dual-source CTCA with 80 kV tube voltage setting can be used to diagnose coronary artery disease and the contrast media lose and radiation dosage can be reduced obviously.